We are studying the biosynthesis, control of biosynthesis and secretion of collagen and elastin in embryonic cartilage and blood vessels. These studies are directed at determining the biochemical modifications of the primary polypeptide chains of these proteins which are necessary for normal secretion from the cell and for normal fiber formation. We are particularly interested in defining the role of hydroxyproline and hydroxylysine. We are studying effects of replacement of proline and lysine in collagen and elastin with amino acid analogues. Such replacement in collagen appears to prevent normal secretion and we are attempting to determine the metabolic fate of these abnormal macromolecules. We are also studying the conformation of the newly synthesized proteins. We are attempting to define at what level synthesis of the molecules is controlled - - that is, at the transcriptional or translational level. We are studying the process whereby the soluble elastin monomer chain is cross-linked into the elastin fiber.